Abstract : The report summarizes briefly the results of five empirical investigations in determinants of social interaction in perceptual judgment and of a large-scale reanalysis of data from previous studies. The major findings are (1) the use of judgments of numerosity of dots in studies of social influence on perception is unwise since a perceptual illusion makes it difficult for subjects to accept influence uniformly through a wide range of stimuli; (2) subjects who are 'socially marginal', or have high scores on Rokeach's test of 'dogmatism' or who are college students with a low level of involvement in extra-curricular activities attend to intra-psychic cues as determinants of social interaction whereas subjects who are not 'socially marginal', or who have low scores on the test of dogmatism or who are campus leaders tend to respond to situational cues. (Author)